The pharmaceutical use of antibodies has increased over the past years. In many instances such antibodies are either injected or infused via the intravenous (IV) route. Unfortunately, the amount of antibody that can be administered via the intravenous route is limited by the physico-chemical properties of the antibody, in particularly by its solubility and stability in a suitable liquid formulation and by the volume of the infusion fluid. Alternative administration pathways are subcutaneous or intramuscular injection. These injection pathways require high protein concentration in the final solution to be injected (Shire et al., “Challenges in the development of high protein concentration formulations”, J. Pharm. Sci. 2004; 93(6): 1390-1402; Roskos et al., “The clinical pharmacology of therapeutic antibodies”, Drug Development Research 2004; 61(3): 108-120. In order to increase the volume, and thereby the therapeutic dose, which can be safely and comfortably administered subcutaneously it has been proposed to use glycosaminoglycanase enzyme(s) in order to increase the interstitial space into which the antibody formulation can be injected (WO2006/091871).
Examples of stable formulations of pharmaceutically active antibodies for therapeutic use currently on the market are as follows:
RITUXAN®/MABTHERA® (Rituximab) is a chimeric antibody which binds to the CD20 antigen on B-cells. The commercial formulation is a sterile, clear, colorless, preservative-free liquid concentrate for intravenous (IV) administration. Rituximab is supplied at a concentration of 10 mg/mL (10 mL) in either 100 mg or 500 mg (50 mL) single-use vials. The product is formulated in 9 mg/mL sodium chloride, 7.35 mg/mL sodium citrate dehydrate, 0.7 mg/mL polysorbate 80, and Water for Injection. The pH is adjusted to 6.5. An alternative liquid formulation for Rituximab suitable for IV administration is disclosed in U.S. Pat. No. 6,991,790.
HERCEPTIN® (Trastuzumab) is a monoclonal antibody directed against the HER2 receptor (anti-HER2) which is currently marketed in Europe in form of a 150 mg lyophilized powder (containing the antibody, α,α-trehalose dihydrate, L-histidine and L-histidine hydrochloride and polysorbate 20) which should be reconstituted for infusions with water for injection to yield injection dose of approximately 21 mg/ml. In the USA and many other countries, a multiple dosage vial containing 440 mg Trastuzumab is marketed.
AVASTIN® (Bevacizumab) is a monoclonal antibody directed against the vascular endothelial growth factor (VEGF) which is currently marketed in Europe as a liquid formulation in two types of vials: a) 100 mg Bevacizumab in 4 ml and b) 400 mg Bevacizumab in 16 ml, respectively, providing a final concentration of 25 mg/ml in water for injection containing the following excipients: trehalose dihydrate, sodium phosphate and polysorbate 20.
While the above antibody formulations have been found suitable for use for intravenous administration there is a desire to provide highly concentrated, stable pharmaceutical formulations of therapeutically active antibodies for subcutaneous injection. The advantage of subcutaneous injections is that it allows the medical practitioner to perform it in a rather short intervention with the patient. Moreover, the patient can be trained to perform the subcutaneous injection by himself. Usually injections via the subcutaneous route are limited to approximately 2 ml. For patients requiring multiple doses, several unit dose formulations can be injected at multiple sites of the body surface.
The following two antibody products for subcutaneous administration are already on the market.
HUMIRA® (Adalimumab) is a monoclonal antibody directed against tumor necrosis factor alpha (TNF alpha) which is currently marketed in Europe in form of a 40 mg dose in 0.8 ml injection volume for subcutaneous application (concentration: 50 mg antibody/ml injection volume).
XOLAIR® (Omalizumab) a monoclonal antibody directed against immunoglobulin E (anti-IgE) which is currently marketed in form of a 150 mg lyophilized powder (containing the antibody, sucrose, histidine and histidine hydrochloride monohydrate and polysorbate 20) which should be reconstituted with water for subcutaneous injection to yield a 125 mg/ml injection dose.
No highly concentrated, stable pharmaceutical anti-CD20 antibody formulation suitable for subcutaneous administration is currently available on the market. There is therefore a desire to provide such highly concentrated, stable pharmaceutical formulations of therapeutically active antibodies for subcutaneous injection.
The injection of parenteral drugs into the hypodermis is generally limited to volumes of less than 2 ml due to this viscoelastic resistance to hydraulic conductance in the subcutaneous (SC) tissue and generated backpressure upon injection (Aukland K and Reed R., “Interstitial-Lymphatic Mechanisms in the control of Extracellular Fluid Volume”, Physiology Reviews”, 73:1-78 (1993)) as well as due to the perceptions of pain.
The preparation of high concentration protein formulations is very challenging and there is a need to adapt each formulation to the particular proteins used because each protein has a different aggregation behavior. Aggregates are suspected to cause immunogenicity of therapeutic proteins in at least some of the cases. Immunogenic reaction against protein or antibody aggregates may lead to neutralizing antibodies which may render the therapeutic protein or antibody ineffective. It appears that the immunogenicity of protein aggregates is most problematic in connection with subcutaneous injections, whereby repeated administration increases the risk of an immune response.
While antibodies have a very similar overall structure, such antibodies differ in the amino acid composition (in particular in the CDR regions responsible for the binding to the antigen) and the glycosylation pattern. Moreover, there may additionally be post-translational modifications such as charge and glycosylation variants.